Probiotics Help Settle Stomachs, Study Says

Updated Nov. 16, 2010 12:01 a.m. ET

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Probiotics, "friendly" bacteria that appear to improve gastrointestinal health, shorten the course of diarrhea by more than a day on average, according to a Cochrane Library meta-analysis. The authors identified 63 medical trials that compared probiotics to placebo or to no probiotics for treating short-term diarrhea in 8,014 people, mostly children. Probiotics, commonly found as a supplement in many yogurts and other foods, are thought to fight diarrhea in a number of ways—perhaps by competing with the pathogens for nutrients or by spurring a stronger immune response. Whatever the reasons, probiotic treatments shortened the course of diarrhea in nearly all the studies, and by an average of 25 hours. (The average total duration of diarrhea in the studies ranged from 39 to 161 hours.) Patients taking probiotics were also 59% less likely to experience diarrhea lasting longer than three days.

Caveat: The trials tested a range of probiotic strains and doses; the meta-analysis could not determine whether certain strains were more effective than others.

Sexually Transmitted Infections: Vaccinating young women against human papillomavirus (HPV) seems to protect not only the vaccinated women against genital warts but also heterosexual men, according to a study in Lancet Infectious Diseases. In 2007, Australia began offering free HPV vaccination to all female residents ages 12 to 26. HPV is the primary cause of cervical cancer, but two particular strains of HPV also cause the vast majority of genital warts. (Not all HPV vaccines target these two strains, but the vaccine offered in Australia, Gardasil, did.) Researchers collected data on 112,083 new patients visiting eight Australian health clinics between January 2004 and December 2009. Until the vaccination program began, the rate of genital-wart diagnoses was fairly stable—around 8% to 9% for women and 12% to 14% for men. But afterward, diagnoses dropped significantly for young women and heterosexual men—by 59% and 28%, respectively. Diagnoses did not decrease, however, for older women (whose vaccinations were not subsidized) or homosexual men. (In the U.S., the FDA has approved Gardasil, and another vaccine, Cervarix, which protects against cervical cancer but not genital warts.)

Caveat: Patients who attended the health clinics may not be representative of the general population, where the rates of vaccination and risky sexual behavior might differ.

Cataracts: Neither vitamin E nor vitamin C protects men against cataracts, according to a study in the Archives of Ophthalmology. The antioxidant vitamins had once been candidates to reduce the risk of developing cataracts (cloudy areas in the eye that can impair vision), since they already play a protective role within eye membranes. Though several recent randomized trials have found little evidence in favor of the treatment, none have followed their participants for more than 6½ years. In this study, researchers randomly assigned 11,545 male doctors to take a daily dose of vitamin C or placebo daily. The same group was also randomly assigned to receive either vitamin E or placebo every two days. After an average of eight years of follow-up, 1,174 of the participants developed cataracts, evenly spread between the vitamin and placebo groups. The vitamins also had no effect on any subtype of cataract.

Caveat: Doctors might have healthier diets than the general population, and thus might derive less benefit from vitamin supplementation. It's also possible that the protective effects of vitamins E and C only emerge after a period even longer than eight years.

Fish Oil: Omega-3 fatty acids, such as those found in fish oil, don't prevent atrial fibrillation from recurring, according to a study in the Journal of the American Medical Association. Researchers recruited 542 patients who had been diagnosed with a short-term form of atrial fibrillation—a condition in which the heart's upper chambers beat irregularly and out of sync with its lower chambers—but no other substantial heart damage. Each patient was randomly assigned to take daily capsules of either omega-3 fatty acids or placebo for six months. Though omega-3s have been associated in observational studies with improved heart health, they provided little benefit in this study: By the end of the six months, atrial fibrillation had returned in 52% of the patients taking omega-3s and 48% of those taking placebo, a statistically insignificant difference. Omega-3s also did not prevent atrial fibrillation recurrences among an additional 121 patients who had a more persistent form of the condition.

Caveat: It's possible that omega-3s protect against atrial fibrillation only in the longer-term. Because the study recruited only otherwise healthy patients, the results might not apply to the elderly, patients with other forms of heart disease, or those who have recently had heart surgery.

Diabetes: Milk proteins in infant formula might play a role in the development of type 1 diabetes, according to a study in the New England Journal of Medicine. Type 1 diabetes, in which the body stops producing insulin, is a highly heritable disease. But its rising incidence, and results from studies of twins, suggest that environmental factors, such as diet, also exert significant influence. Finnish researchers recruited 230 breast-fed babies with a family history of the disease. The babies' mothers were randomly assigned to wean their infants to either (a) standard cow's-milk-based infant formula, or (b) formula that had been extensively "hydrolyzed" to break down the milk proteins into much smaller parts. By age 10, blood tests revealed that 30% of children given the standard formula had developed at least one diabetes-associated antibody, compared with only 17% of children who received the broken-down formula.

Caveat: Despite the differences in antibodies, the broken-down formula did not reduce the number of type 1 diabetes diagnoses. About 6% of children receiving the broken-down formula developed the disease, compared to 8% of children who received the standard formula—a statistically insignificant difference.

Gout: Women who drink sugary beverages most often are more likely to develop gout, according to a study in the Journal of the American Medical Association. Gout, a particularly painful form of arthritis caused by uric acid accumulating around the joints, predominantly afflicts men but may affect up to 5% of women over age 70. Fructose, one of the two sugar molecules in sucrose, is known to increase levels of uric acid. Since 1984, nearly 79,000 female nurses have been reporting how frequently they drink soda and fruit juices, as part of a larger study. Based on 22 years of follow-up, the authors determined that drinking at least one serving of sugar-sweetened soda per day was associated with an extra 3.6 cases of gout per 10,000 women each year, compared with drinking less than one serving per month. The same difference in orange-juice consumption was associated with 1.4 extra gout cases per 10,000 women each year. Diet soda and all other fruit juices, however, weren't significantly associated with gout.

Caveat: The food frequencies were based on the nurses' own recollection, rather than a more systematic measurement. It's impossible to tell from the data whether fructose consumption caused the extra gout cases, or was merely associated with them.

Reading: People read letters in short words simultaneously, rather than from left to right, according to a report in Psychological Science. Researchers showed 98 adult participants a series of four-letter words, each appearing on a computer screen only briefly—somewhere between 12 milliseconds and 54 milliseconds. Following each word, the researchers asked the participants to determine which of two words they had seen. In nearly half of the cases, the two options differed by just one letter—"sung" versus "lung", for instance. When a word appeared for just 18 milliseconds, the participants appeared to be randomly guessing, no matter which of the four letters had been swapped. But when the words appeared for 24 milliseconds, participants' guessed more accurately than they would have by pure chance. Because accuracy jumped for all the letter positions at once, the letters had likely been processed simultaneously. Though participants identified words more accurately when left-side letters had been swapped than when right-side letters had been swapped, the researchers attributed this bias to a difference in efficiency rather than sequence.

Caveat: The study did not test reading patterns for longer words, or for words in different alphabets. The researchers did not present data on educational attainment, which may affect reading patterns.

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